You can buy the pattern individually or as part of an ebook with the other two Linen Weave shapes.

For those who love linen stitch, but prefer a triangle shape: Linen Weave Triangle …

(this was actually the original).

Note that it’s a long shallow triangle designed to be worn as a scarf or just across the top of the shoulders, not a traditional triangle-shaped shawl.

You can use with any weight of yarn from fingering to aran with the suitable needle size (because it’s linen stitch the needle size will be 1-3 sizes larger than you’d usually use for that weight of yarn - more details in the pattern).